Considerable research suggests that the behavioral tolerance which develops in animals when they are repeatedly exposed to some drugs is based to some extent upon learning. Although this has been well-demonstrated with many drugs, especially the opiates, one apparent exception has been ethanol. Several influential experiments have led to the conclusion that "learning" or behavioral practice while being intoxicated can speed up the rate of development of tolerance, but cannot alter the final or asymptotic level of tolerance achieved. The term, Behavioral Augmentation of Tolerance or BAT, has been applied to this phenomenon. Pilot research in our lab has replicated these earlier experiments and added sufficient extra controls to question this interpretation. In fact, a number of studies in our lab suggest rather clearly that learning, not merely drug exposure, is necessary for the development of tolerance to ethanol. The proposed research is intended to demonstrate this in a less ambiguous manner. In one of the experiments, complete dose-effect curves will be obtained on rats rendered tolerant and on rats given comparable amounts of ethanol but with no tolerance; i.e., with a differential amount of previous intoxicated practice. In other studies, rats which have previously received considerable ethanol but which are not "tolerant" will be given several trials of intoxicated practice to determine if their experience with the drug imparts a benefit in terms of a faster rate of development of tolerance. Still other proposed experiments will explore the possibility that rats can be rendered tolerant without the necessity of ever receiving a drug at all. These studies are based on the assumption that tolerance is simply a learned compensatory response. The basic model in all of the proposed experiments is the treadmill, a device which monitors walking behavior and which is an accepted model for studying the development of tolerance. Collectively, the proposed experiment will explore many parameters of learning and tolerance and the implications of such an interaction.